The present invention relates to systems for transporting high solid sludge (which includes slurries and mixtures of organic or inorganic solids, liquids, and gases such as air). In particular, the present invention relates to sludge flow measuring systems used in conjunction with a positive displacement pump to measure and monitor flow of sludge by determining a fill percentage during each pumping stroke.
Sludge flow monitoring systems were introduced in the early 1990's, and have been the subject of a number of patents, including U.S. Pat. No. 5,106,272 (reissued as Reissue 35,473), entitled “Sludge Flow Measuring System”; U.S. Pat. No. 5,257,912, entitled “Sludge Flow Measuring System”; U.S. Pat. No. 5,336,055, entitled “Closed Loop Sludge Flow Control System”; U.S. Pat. No. 5,330,327, entitled “Transfer Tube Material Flow Management”; and U.S. Pat. No. 5,346,368, entitled “Sludge Flow Measuring System”.
Sludge flow measuring systems have defined a standard for measurement of the volume of material delivered by a sludge pump through a pipeline. Some applications, however, require even greater accuracy than has been available in the past from sludge flow monitoring systems. High accuracy would be of great importance to the user in those cases where compensation is based upon the actual volume of material that has been pumped.